Prepare recombinant DNA "libraries" from a number of wild mice species. Screen these libraries by filter hybridization with a variety of immunoglobulin probes provided by the project officer. Isolate positive recombinants and characterize by restriction endonuclease digestion. Subclone fragments of interest into designated plasmid vectors. Grow subcloned plasmids in preparative amounts and supply to project officer for further analysis.